1. Technical Field
The present invention relates generally to an apparatus and method for generating a group key using the status of a wireless channel and, more particularly, to an apparatus and method for generating a group key using the status of a wireless channel, in which a wireless communication terminal transmits a pilot signal by varying transmission power in a wireless network environment, thus generating a group key.
2. Description of the Related Art
A large number of encryption technologies have been applied to and used in wireless communication systems. However, these technologies are problematic because legal users depend on the fact that it is difficult for an eavesdropper to calculate keys rather than the fact that it is mathematically impossible for the eavesdropper to obtain keys. Further, as computational ability that can be used by eavesdroppers increases, the effect of such a technology decreases. Therefore, it is more profitable to construct encryption technology that provides absolute secrecy rather than being based on the assumption of computational difficulty.
Meanwhile, a centralized private key distribution scheme is not suitable for an ad-hoc network or a peer-to-peer network which is a new wireless communication environment. Since this wireless communication environment is not controlled by a central system, it is impossible to implement a centralized private key distribution scheme, and a new key generation scheme that replaces the above scheme is required.
In a wireless communication network, mutually related random sources for providing absolute secrecy can be obtained from wireless channel information. In particular, when a wireless communication system is implemented in a Time Division Duplex (TDD) manner, two users A and B between which a communication link has been established can respectively obtain the same wireless channel information for a specific period of time.
In contrast, an eavesdropper, the wireless link of which is not established with the users A and B will observe the status of a wireless channel having little correlation with the wireless channel of the users. This difference an be used to generate a perfect private key. The two users can generate a private key using pieces of wireless channel information observed at regular time intervals. Such a private key generation scheme is advantageous in that there is no need to distribute or generate a key at a central system because a subject for performing communication directly generates a key.
The above private key generation scheme using the wireless channel has been proposed as a scheme for generating a private key using a channel impulse response that is spontaneously generated in a communication link between users who perform wireless communication. Further, such a private key generation scheme using the wireless channel is limited to the generation of a private key between two terminals. However, there also occurs the case where the use of a group key to be used by two or more terminals in common is required, which takes place depending on the properties of the transmission data.